This is probably the 3rd, 4th, or maybe even 5th book I have read about ISIS. It is by far the most comprehensive and details how they arose along with their competition with al Qaeda.
This book details how and why they became successful at recruiting and using social media to do so and how some of these successes have also backfired on them.
This is the first book that has detailed ISIS from what they believe, to their leadership, to how they operate and fund themselves, and the propaganda techniques they use to subject the people in their reign of terror.
This is also the first book that has detailed ways to stop them and stopping them is not just by military means, e.g. air strikes or boots on the ground and it is not going to happen in a few months, a few years, or even a decade and will likely take a generation or two to root out their evil ideology.
This is a great book that I highly recommend to fully understand the thread ISIS poses and how to stop them and it's a lot more than what you get from watching a 30-120 second spot on any American Main Stream Media channel.